Context
As shown in FIG. 1, according to 3G WCDMA (Third Generation Wideband Code Division Multiple Access), in communicating via wireless communication, a mobile user equipment (UE) 18 interfaces with a UTRAN (universal mobile telecommunications system (UMTS) terrestrial radio access network) Node B 17 (also sometimes called a base station) over a so-called Uu interface. The UTRAN Node B in turn communicates with a UTRAN radio network controller (RNC) 11 over a so-called Iub interface, and the RNC communicates with a core network (CN) entity, either a mobile switching center (MSC) or a serving GPRS (general packet radio system) support node (SGSN), over a so-called Iu interface, and also communicates with other RNCs over a so-called Iur interface. The Iu interface is more specifically either an Iu circuit-switched interface IuCS between a UTRAN RNC and an MSC, or an Iu packet-switched interface IuPS between a UTRAN RNC and an SGSN.
There are a set of protocols used by a UE and a UTRAN in communicating across the Uu interface which are jointly called the WCDMA protocol; the different protocols making up WCDMA are called protocol layers. The lowest layer, as illustrated in FIG. 2A, is a physical layer (PHY), denominated layer 1 (L1), and resides in the UE, the node B and the RNC, although an MDC (macro-diversity combining) component of L1 does not reside in node B and that component is the only component of L1 that resides in RNC; however, by locating the MDC component of L1 in RNC, soft handover can be supported, during which data coming from different branches are macro-diversity combined in the RNC. A layer 2 (L2) resides in RNC and, in case of configurations supporting HSDPA (High Speed Downlink Packet Access), also resides in node B. See FIG. 2A showing L2 only in RNC and see FIG. 2B showing L2 extended to reside in both RNC and node B as the MAC-hs entity in node B. L2, in general, consists of a media access control (MAC) sublayer and a radio link control (RLC) sublayer, as well as other sublayers not relevant to the invention, such as the PDCP (Packet Data Convergence Protocol) sublayer and the BMC (Broadcast Multicast Control) sublayer. PHY offers transport channels to the MAC sublayer, which in turn offers logical channels to the RLC sublayer.
Note that the data flows from the FP layer over the Iub interface are different in FIG. 2A (showing case for configuration not supporting HSDPA) and FIG. 2B (showing case for configuration supporting HSDPA). A transport channel is defined in UTRAN as a channel between the MAC layer (excluding MDC) and L1, and therefore in a case where HSDPA is not supported, transport channels exist on Iub interface. Also, because Node B in such a case does not contain any L2 functionality, the PDU (Protocol Data Unit), which is transmitted over the Iub interface, is a Transport Block (equal to a MAC PDU), i.e., no additions or changes the MAC PDU/Transport Block are made by Node B.
However, in case of a configuration supporting HSDPA, as in FIG. 2B, L2 is extended to the Node B, and if transport channels are defined to be all channels between MAC layer and L1, then in this case the transport channel is a channel between MAC-hs and L1, i.e. it is an internal channel in Node B. On Iub, the data packet is transmitted as a MAC-d PDU, so that the packet is not a complete MAC PDU. Before it is made into a complete MAC PDU, the packet must be processed by MAC-hs, which adds a MAC-hs header at the head of an already existing MAC-d header. Thus, the structure of the PDU is not complete when it comes to the Node B. Therefore there are different names for the data flows from the FP layer over the Iub interface for the case of a configuration supporting HSDPA and one that does not.
The WCDMA FDD (frequency division duplex) communication between a UE and an SRNC through the defined protocol stacks is illustrated in FIGS. 3A-C for three different applications. FIGS. 3A and 3B illustrate the protocol stacks for the DCH (dedicated channel, a transport channel) and DSCH (dedicated shared channel), respectively. The data coming from the DTCH (dedicated traffic channel) and DCCH (dedicated control channel) logical channels are mapped either onto the DCH (as in FIG. 3A) or the DSCH (as in FIG. 3B), using the services of MAC-d or MAC-d/MAC-c/sh, respectively. From the MAC layer, the data are communicated to a Node B using the services of the FP layer. At the node B, the data are provided to the UE over the air interface via the services of L1.
FIG. 3C illustrates the case when the configuration provides support for HSDPA. In this case the data, which is received from the RLC layer by the MAC layer over logical channels, are mapped onto so-called MAC-d data streams using the services of the FP layer. At a Node B, these MAC-d data streams are mapped to physical channels using the services of the MAC-hs and L1. The protocol stacks in FIGS. 3A-C all use, for the TNL (Tranport Network Layer, discussed below) at the Iub and Iur interfaces, the service of ATM (Asynchronous Transmission Mode) and AAL2 (ATM Adaptation Layer Type 2) protocols.
It should be understood that in case of an HSDPA application, such as illustrated in FIG. 3C, the MAC-d data streams correspond to the transport channels at an Iub interface.
As illustrated in FIG. 4, the general protocol model for UTRAN interfaces consists of two main (horizontal) layers, the Radio Network Layer (RNL), and the Transport Network Layer (TNL). All UTRAN telecom-related issues are visible only in the RNL, and the TNL represents standard transport technology that is selected to be used for UTRAN, but without any UTRAN specific requirements. The RNL includes layers 1-3. The TNL provides the capability of transporting the Frame Protocol PDUs and Application Protocol signalling messages over Iub, Iur, and Iu, using ATM technology. ATM technology refers not only to ATM protocol but to all related protocols (ATM, AAL2, AAL5) and to any physical transmission appropriate for an ATM interface. The TNL at the Iub interface manages only ATM-related issues. All other functions and protocol layers are handled by the RNL.
As is indicated in FIG. 4, the general protocol model for UTRAN Interfaces also consists of three (vertical) planes: a Control Plane, a Transport Network Control Plane, and a User Plane. The Control Plane includes the so-called Application Protocol and the Signalling Bearer for transporting the Application Protocol messages. Among other services it provides, the Application Protocol is used for setting up bearers (i.e. a Radio Bearer and a Radio Link) for the RNL. In the three-plane structure, the bearer parameters in the Application Protocol are not directly tied to the user plane technology, but are rather general bearer parameters. The Signalling Bearer for the Application Protocol may or may not be of the same type as the Signalling Bearer for the ALCAP (Access Link Control Application Part). The Signalling Bearer is always set up by Operations and Management (O&M) actions (under the direction of an Operations and Management Center or OMC).
The User Plane includes the data streams and the data bearers for the data streams. The data streams are characterized by one or more frame protocols (FPs) specified for that interface.
The Transport Network Control Plane does not include any RNL information, and is completely in the Transport Layer. It includes the ALCAP protocol(s) needed to set up the transport bearers (Data Bearers) for the User Plane. It also includes the appropriate Signalling Bearers needed for the ALCAP protocols.
Also as illustrated in FIG. 4, the Data Bearers in the User Plane and the Signalling Bearers for the Application Protocol both belong to a Transport Network User Plane. (As mentioned, the Data Bearers in Transport Network User Plane are directly controlled by the Transport Network Control Plane during real-time operation, but the control actions required for setting up the Signalling Bearers for Application Protocol are considered O&M actions.) Thus, there is a Control Plane and a User Plane when viewed from the RNL, and a differently constituted (Transport Network) User Plane and (Transport Network) Control Plane when viewed from the TNL.
The End-to-End Bearer Service and the UMTS Bearer Service are illustrated in FIG. 5. On its way from a TE (terminal equipment, and can be part of a UE, as indicated as an MT in FIG. 5) to another TE, the traffic must pass different bearer services of one or more networks. A TE is connected to the UMTS network by use of a Mobile Termination (MT), which in combination with the TE makes up a UE. The End-to-End Bearer Service on the application level uses the bearer services of the underlying networks, and is conveyed over several networks, not only the UMTS network. The End-to-End Bearer Service used by a TE is realized using a TE/MT Local Bearer Service, a UMTS Bearer Service, and an External Bearer Service.
The Problem Solved By The Invention
According to 3GPP TSG RAN specifications (such as e.g. 3GPP TS 25.401), when an RNC is communicating with a Node B so as to ultimately communicate with a mobile phone, (see FIG. 2), each transport channel is conveyed across an Iub interface by a dedicated AAL2 connection (see FIG. 3), which is provided to a Frame Protocol (FP) layer 16 (see FIG. 2). An AAL2 connection is one realization of a transport bearer in UTRAN. The FP layer 16 is a part of the RNL, whereas the AAL2 is a part of the TNL. The WCDMA L1, as a part of the RNL, can provide macrodiversity for the data streams when they are in soft handover; in other words, the WCDMA L1 can handle the same UE data streams from two different Node Bs. Otherwise, the WCDMA L1 of the RNL is transparent to the data stream, i.e. the WCDMA L1 of the RNL does not in any way affect or process the data stream if the mobile phone is not in soft handover. (This is a simplification and may not always be true; the WCDMA L1 is always doing processing like interleaving/deinterleaving and channel coding/decoding in the Node B for each data stream.)
Note that there is an L1 for the RNL (WCDMA Layer 1), which handles macrodiversity and there is an L1 functionality for the TNL (TNL Layer 1), which handles the physical transmission below the ATM protocol on TNL. The RNL/TNL protocol stack cannot be compared with the seven-layer open systems interconnect (OSI) model.
The specifications further provide that the transport bearers (i.e. AAL2 connections in case of ATM transport) are controlled (set up, released, modified) by an AAL2 signaling protocol, which allows transport bearers to have a bit rate of up to a maximum of 2048 kbit/s. In UTRAN Rel5 (release 5), transport channels are specified that can exceed the 2048 kbit/s maximum rate of the AAL2 signaling protocol.
Therefore, what is now needed (because of release 5) is a way to enable a UTRAN (and more specifically an RNS) to use the AAL2 signaling protocol with transport channels conveying user and/or control data at bit rates in excess of the maximum of 2048 kbit/s, or in other words, a way to provide an AAL2 connection with (high capacity) radio bearers per UTRAN Rel5. Ideally, what would be provided could be used at both an Iub interface and an Iur interface.